This invention involves flexible polyurethane foams, preferably such foams based on natural oil polyols and having high resilience.
Foamed articles, especially polyurethane foamed articles are known for many years and used in many applications, especially for automotive seating, cushioning and mattresses. Polyurethane foams are referred to as high resilience (HR) if they have a resilience indicated by ball rebound of greater than about 40 percent measured according to the procedures of ASTM D3574 Test H. High resilience foams are usually foamed using petroleum based polyols having a nominal functionality of an average of about 3 hydroxyl groups per molecule and an average molecular weight range of about 5,000. Such foams are produced at an isocyanate index of from 65 to 115, typically using water levels at most about 5.0 parts by weight per 100 parts by weight per hundred parts polyol (pphp).
It is desirable to use isocyanates based on methylene diphenyl diisocyanate (MDI) because of lower vapor pressure as compared with TDI (Toluene diisocyanate), hence lower potential toxicity; however, it was shown by K. D. Cavender, et al “New Considerations in Isocyanate Selection for Automotive Seating Foams” in 32nd Annual Polyurethane Technical/Marketing Conference, Oct. 1-4, 1989, pages 594-595, Technomic Publishing Co, 851 New Holland Avenue, Box 3535, Lancaster, Pa. 17604, USA, that MDI based HR foams have lower ball rebound values than TDI (toluene diisocyanate) based foams (48 percent for MDI foams as compared with 68 percent for TDI foams at equivalent foam hardness).
It would also be desirable to use starting materials produced from renewable resources like biological, especially plant, based materials rather than petroleum based materials. In the case of polyurethanes, it is the polyol that is sometimes based on plant materials. However, using natural oil based polyols to replace conventional polyols in HR foams has been shown to decrease ball rebound values as disclosed by Examples 53 to 56 of WO 2004/096882.